<?php

function getimg($link)
{
	$context = stream_context_create(array(
		'http' => array(
			'timeout' => 3000 //超时时间，单位为秒
		) 
	));
	$content = file_get_contents($link, 0, $context);	//获取地址
	$temp = substr($content,strpos($content,"screenshot="));
	$img = substr($temp, 11, strpos($temp,"\"")-11);
	return $img;
}

echo getimg('http://v.youku.com/v_show/id_XMzc2NDkzNTY0.html');

?>